Reaction wells, assembly thereof, immunoassay apparatus and method using such well assemblies

ABSTRACT

The present invention relates mainly to reaction vessels, to sets of such vessels for automatic immunological assay apparatuses, to automatic immunological assay apparatuses making use of such sets of vessels, and to a method implementing sets of such vessels. According to the present invention, photometric detection is implemented of the luminescence of a reaction mixture found in a reaction vessel, the apparatus and/or the vessel guaranteeing light-tightness so as to prevent entry of external light falsifying the measurement. Advantageously, sets of vessels in accordance with the present invention are made out of a material that is opaque. The present invention is particularly applicable to detecting the presence of a chemical or a biological substance in a sample. The present invention applies mainly to medical analysis and research.

This is the National Stage Application of PCT/FR99/02170 filed Sep. 13,1999.

The present invention relates mainly to reaction vessels, to sets ofsuch vessels for automatic apparatuses for immunological assay, toautomatic apparatuses for immunological assay implementing such sets ofvessels, and to a method implementing sets of such vessels.

BACKGROUND OF THE INVENTION

FR 96/12546, WO 91/107662, and WO 96/14582 disclose automaticapparatuses for immunological assay essentially comprising means forsupporting, guiding, and stepwise displacement of reaction vessels alonga path having a predetermined number of positions, a turntablesupporting samples to be analyzed, a turntable supporting reagents,means for taking determined quantities of samples and of reagents, andfor injecting said taken quantities into the reaction vessels, means forwashing the vessels, means for optically reading the results of theassays, and a controlling computer system enabling preprogrammed assaycycles to be performed corresponding to single-reagent or two-reagentassays, said known apparatuses operating at a rate of about 120 assaysper hour to 360 assays per hour for the second apparatus.

The apparatus described in international application WO 96/14582 alsodiffers in that it is designed to operate with reaction modules whichare parts molded out of transparent plastics material and comprise aplurality of reaction vessels in alignment that are secured to oneanother, said reaction modules being mass-produced at a very low costprice, thus making it possible to discard them after a single use.Furthermore, such reaction modules are suitable for stacking, thusmaking them easier to package and also making it easier to stack them inautomatic feed means of the apparatus.

FR 96/12546 proposes apparatus of the above-specified type, comprisingmeans for supporting, guiding, and stepwise displacement of sets ofreaction vessels along a path comprising a predetermined number ofpositions, means for supporting samples to be analyzed, means forsupporting reagents, means for taking determined quantities of samplesand of reagents, and for injecting the taken quantities into thereaction vessels, together with means for washing the vessels, means forreading the results, and means for feeding sets of reaction vessels andfor ejecting sets of used vessels, wherein the path of the sets ofreaction vessels is rectangular in shape and has two long sides definedby parallel rectilinear support and guide rails for the sets of vessels,and two short sides defined by means for displacing the sets of vesselstransversely over three positions comprising two end positions on thelong sides of the path and an intermediate position which constitutesthe position for ejecting a set of used vessels and the position forfeeding a set of new vessels.

Those apparatuses use color-measuring means for reading results throughthe light-transparent walls of the vessels.

Automatic apparatuses are also known for performing immunological assay,which apparatuses are provided with means for reading the luminescenceof the reaction mixture. The apparatuses of known types comprise a darkchamber fitted with light-measuring means for measuring brightness,means for transferring reaction mixtures from a vessel into the darkchamber, means for washing the dark chamber and transfer means, andmeans for decontaminating the dark chamber and transfer means. As aresult, such automatic immunological assay apparatuses are extremelycomplex and present a cost price that is high.

OBJECTS AND SUMMARY OF THE INVENTION

Consequently, an object of the present invention is to provideimmunological assay apparatus that is simple, having means for detectingthe luminescence of the reaction mixture.

Another object of the present invention is to provide apparatus that isextremely reliable, always providing results that are accurate andrelevant.

It is also an object of the present invention to provide such anapparatus that is capable of operating at high rates of throughput.

It is also an object of the present invention to provide an apparatusthat presents a cost price that is moderate.

According to the present invention, these objects are achieved byimplementing photometric detection of the luminescence of a reactionmixture in a reaction vessel, the apparatus and/or the vessel providinglight-proofing so as to prevent external light entering and falsifyingthe measurement. Advantageously, the sets of vessels in accordance withthe present invention are made out of a material that is opaque.

Preferably, the light-tightness of each assembly constituted by thephotometric detection device associated with a vessel filled withreaction mixture is tested.

The invention mainly provides a reaction vessel for automatic apparatusfor immunological assay, the vessel comprising walls in the form of avessel for receiving a sample to be tested, a test reagent, and asubstrate coupled with a chemiluminescent substance, and also a fillingopening, wherein the walls are proof against any light emitted by thechemiluminescent substance, apart from a window for reading theintensity of any light emitted by the reaction mixture formed by thesample to be tested, the reagent, and the substrate.

The invention also provides a vessel wherein the read window correspondsto the filler opening of the vessel.

The invention also provides a vessel wherein the read window issurrounded by a substantially plane zone against which a light-proofshoe is pressed.

The invention also provides a plurality of vessels according to anypreceding claim.

The invention also provides automatic apparatus for immunological assay,comprising means for supporting, guiding, and stepwise displacement of areaction vessel or sets of reaction vessels along a path comprising apredetermined number of positions, means for supporting samples to beanalyzed, means for supporting reagents, and means for taking determinedquantities of samples and of reagents and for injecting the quantitiestaken into the reaction vessels, together with means for washing thevessels, means for reading the results, and means for feeding sets ofreaction vessels and for ejecting sets of used vessels, the apparatusincluding means for forming a temporary dark chamber that is proofagainst external light, said dark chamber having photometric means formeasuring the intensity of light and a vessel or a vessel from a set ofvessels.

The invention also provides apparatus including an opaque shoe forpressing in light-proof manner around a read window of a reaction vesselprovided with a central opening for passing light between the vessel andphotometric means.

The invention also provides apparatus including a plate for receivingthe washing means and the photometric means.

The invention also provides apparatus wherein the photometric meansinclude moving equipment for pressing the shoe against the read windowof the reaction vessel.

The invention also provides apparatus including a shutter for opticallyisolating a photoelectric detector, in particular a photomultiplier, andmeans for measuring the electrical values delivered by the photoelectricdetector while it is immersed in the dark, the shutter being closed.

The invention also provides apparatus wherein movement of the movingequipment serves to close or open the shutter.

The invention also provides apparatus including a light source forilluminating, on command, the outside of the dark chamber formedtemporarily by the walls of the vessel and the photometric means so asto enable the dark chamber to be tested for light-tightness, theimmunological test being rejected if the photometric means detect lightemitted by the light-tightness testing source.

The invention also provides apparatus performing a light-tightness testfor each reaction vessel subjected to an immunological test.

The invention also provides an automatic method of performingimmunological assay, the method comprising a step of detecting thelight, if any, emitted by a substrate coupled with a luminescentchemical substance in the presence of a reagent and a sample to betested, the method including a step of measuring: the light intensitypresent inside a reaction vessel.

The invention also provides a method wherein a temporary dark chamber isformed with a reaction vessel having an opaque wall and with photometricmeans.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from the following descriptionand the accompanying figures given as non-limiting examples and inwhich:

FIG. 1 is a plan view of the preferred set of vessels of the presentinvention;

FIG. 2 is a perspective view of: the FIG. 1 set;

FIG. 3 is a diagrammatic plan view of a preferred embodiment ofapparatus of the present invention;

FIG. 4 is a diagrammatic elevation view of a washing and detectiondevice for the apparatus of FIG. 3, with sets of vessels being shown inplan view and on the same scale;

FIG. 5 is a vertical section view of a photometric measuring deviceimplemented in the apparatus of the present invention and shown in arest condition or a condition for calibrating the measured photometricvalue for darkness; and

FIG. 6 is a view of the FIG. 5 device in vertical section on a planeorthogonal to the plane of FIG. 5.

MORE DETAILED DESCRIPTION

In FIGS. 1 to 6 the same references are used to designate the sameelements.

In FIGS. 1 and 2, there can be seen the preferred embodiment of a set 26of reaction vessels 28.

The sets 26 of reaction vessels 28 are made as one-piece moldings ofopaque plastics material, in particular of filled polystyrene, each setcomprising eight reaction vessels 28 in alignment on a longitudinal axis45 of the assembly 26 and connected to one another, each set having twoL-shaped top longitudinal rims 30 extending higher than the open topends of the vessels 28.

Each longitudinal rim 30 includes, in register with each vessel 28, afrustoconical orifice 32 for use in accurately positioning the set 26 incertain stations of the apparatus of the invention, and each of theouter side faces of the rims 30 has a pair of vertical ribs 34 forco-operating with means for driving the sets 26.

As already described in international application WO 96/14582, thevessels 28 are segments of rectangular-section tube closed at theirbottom ends and flaring at their top ends, thereby enabling sets 26 tobe stacked vertically while being partially received in one another,with the bottom portion of the vessels 28 in one set 26 penetrating intothe flared top ends of the vessels 28 of an underlying set of reactionvessels. This engagement is made easier by the fact that the insidefaces of the longitudinal rims 30 diverge slightly apart from each otherin an upward direction starting from the open top ends of the vessels28.

Vertical ribs 36 are formed on the flanks of the enlarged top ends ofthe vessels 28 and extend a short distance downwards, the bottom ends ofthe ribs 36 being designed to come into abutment against the top facesof the rims 30 of an underlying set 26 in a vertical stack of sets ofreaction vessels.

In addition to being made of opaque material, the sets 26 of vessels inaccordance with the present invention differ from those of FR 96/12546and WO 96/14582 in that each opening 37 of a vessel 28 is surrounded bya substantially plane rim 39 against which an opaque shoe 41 can bepressed (FIGS. 4 to 6), so as to prevent external light from penetratinginto a photometric measuring device 43.

The rim 39 is advantageously constituted firstly by a space 39′ betweenvessels and secondly by two margins 39″ situated between the walls 30′of the rim 30 and the longitudinal walls 28′ of the top portions of thevessels 28.

Naturally, the present invention is not limited in any way to the shapeor the material used for the sets 26 of reaction vessels 28.

In a variant, it is possible to use vessels or sets of vessels that aresuitable for other kinds of automatic apparatuses for performingimmunological assay or to use vessels made using a transparent materialthat is covered in an opaque layer, e.g. a layer of metallization.Similarly, with a vessel 28 of the present invention it is possible toenvisage performing photometric measurement of the luminescence of thereaction mixture through a wall thereof that is not entirely opaque,providing the luminescence coming from a given vessel can be completelyisolated from luminescence coming from any adjacent vessel.

For example, it is possible to envisage providing transparent readwindows or incorporating a light guide, e.g. in the form of a shortoptical fiber in the bottom or the side walls parallel to a verticalplane including the longitudinal axis 45 of the set 26. Under suchcircumstances, the photometric detector means comprise means forisolating the cell being read, such as masks or a shoe analogous to theshoe 41, for example.

The apparatus of the invention whose general structure is shown verydiagrammatically in FIG. 3, comprises a frame 10 having mounted thereonboth a turntable 12 for supporting samples to be analyzed and aturntable 14 for supporting assay reagents, together with means 16, 18for taking determined quantities of samples and of reagents respectivelyand for depositing said taken quantities in a reaction vessel, saidmeans being of the same type as those described in internationalapplication WO 96/14582 and FR 96/12546, the contents of which areincorporated herein by reference.

The reagents used are of the magnetic bead type and the apparatus of theinvention comprises means 20 for washing or rinsing such magnetic beads,which means are of the same type as those already described in theabove-specified applications and have vertically-displaceable needlesfor sucking up and injecting liquid, together with permanent magnetslocated on either, side of the path of the reaction vessels 28 so as toattract by magnetic attraction the magnetic beads carrying the reagentsand fix them temporarily on the walls of the reaction vessels. The means20 also have a needle for depositing a chemiluminescent substrate in thereaction vessels 28, located immediately downstream from the needles forinjecting and sucking up washing liquid.

Photometric means 22 for optical reading purposes comprise means 43 formeasuring light intensity at the wavelengths of the luminescence of thesubstrate used. By way of example, a substrate is used containing adisodium salt of4-methyoxy-4-(3-phosphonatephenyl)spiro[1,2-dioxethane-3,2′-amandane]and sold by LUMIGENE under the reference lumi-Pho 530® which emits inthe visible light range with an emission peak correspondingsubstantially to 530 nm. Under such circumstances, a visible lightdetector is used whose passband may optionally be narrowed by using afilter that passes only those frequencies that are likely to be emitted.Although using solid state detectors, and in particular semiconductordetectors does not go beyond the ambit of the present invention, thepreferred embodiment of the apparatus of the invention uses aphotomultiplier tube. The preferred embodiment uses a photomultiplier assold by HAMAMATSU under the reference H 7155-20.

This type of tube presents the advantage of being able to work atambient temperature thus making it possible in the preferred embodimentof the invention to provide a machine that does not have any cryostats.Nevertheless, prior to each measurement of the luminescence of areaction mixture, the apparatus of the invention advantageously performsa measurement in the absence of any light, in the dark, so as tocalibrate the reading, in particular the electric voltage, thatcorresponds to complete darkness. This improves the reliability and therepeatability of measurements, particularly when the volume in which thesets 26 travel is thermostated at 37° C., for example, in order to favorincubation of the reaction mixture.

The output from the photomultiplier 43 is connected via interface andmatching means to a computer for monitoring the machine, making use ofthe results, and/or managing them. For example, the output from thephotomultiplier is connected via analog matching means, in particular ofthe type comprising amplifiers or frequency matching means, to ananalog-digital converter whose output is connected to an acquisition,metering, and control card installed in a microcomputer, e.g. of the PCtype (not shown).

In the advantageous embodiment shown in FIGS. 3 and 4, a common plate47, e.g. comprising a top plate 47.1 and a bottom plate 47.2 (FIG. 4)carries the washing head 20 and the photometric means 22.

In FIG. 4, the needles for injecting or taking samples are givenreferences 49, while the indexing studs that penetrate into the openings32 are given the reference 51. Advantageously, the first two indexingstuds 51 are united by a spring 55.

The sets 26 of vessels 28 together with magnets 53 oriented in thenorth-south or the south-north direction are shown in a plane in FIG. 4so as to give the scale of the plate 47 that has the means 20 and 22.

The apparatus of the invention also has means for displacing the sets ofreaction vessels along a path of rectangular shape, with automatic feedmeans 24 being located at one end thereof to feed it with sets ofreaction vessels and also for ejecting such vessels.

Advantageously, the apparatus of the present invention has externalbodywork and internal caps of material that is opaque or partiallyopaque so as to restrict the amount of light that can reach the readwindow of the photometric means 22.

Advantageously, the apparatus of the present invention has a lightsource 57, e.g. a light-emitting diode (LED), for verifying the opticalisolation of the measurement cavity as formed by the vessel beingmeasured in association with the photometric means 22.

In the advantageous embodiment shown, in particular in FIGS. 5 and 6,the photometric mean's 22 comprise the photomultiplier 43 which is fixedrelative to the bottom plate 47.2 and moving equipment 59. By way ofexample, the moving equipment comprises a shutter 61, and a light guide63 housed in an opaque rigid tubular duct 65 that opens out via anopening 67 in the opaque shoe 41. A rail 67 provides guidance between alow position as shown in FIG. 5 in which the shutter 61 opticallyisolates the photomultiplier 43 from the light guide 63 and a highposition as shown in FIG. 6 in which the shutter 61 is retracted so asto allow communication between the light guide 63 and thephotomultiplier 43.

Return means 69, e.g. a helical spring surrounding the rigid tubularduct 65, ensure that the moving equipment 59 returns to the low positionshown in FIG. 5. In the advantageous embodiment shown, the shutter 61 isa rotary shutter that is rotatable about an axis of rotation 71 and thathas return means, e.g. a helical spring 73 operating in traction forreturning it towards the closed position. In the non-limiting exampleshown, the shutter 61 closes the end of the light guide 63 when themoving equipment 59 is in its low position as shown in FIG. 5, and movesout of the way when the moving equipment 59 is in its high position asshown in FIG. 6.

Naturally, implementing other types of shutter, in particular linearshutters, curtain shutters, or shutters that mask an inlet window to thephotomultiplier 43, or even implementing photometric means 22 withoutany shutter, would not go beyond the ambit of the present invention.

The apparatus of the present invention operates as follows:

The apparatus 10 is loaded firstly with reagents and the substrate, andsecondly with the samples (serum) to be tested.

During a first revolution lasting 15 minutes, the vessels 28 of the sets26 receive from the device 16 the samples to be tested. The sets 26 aredriven by the belt 40.

During a second revolution that lasts 15 minutes, the vessels 28 receivethe reagents from the device 18.

During a third regulation that lasts 15 minutes, the means 20 wash themagnetic balls and the luminescent substrate is inserted.

During the following revolution (lasting 15 minutes), the result of thetest is revealed and then read. Advantageously, to read each vessel 28,the dark level is initially calibrated, i.e. the voltage available atthe outlet from the photomultiplier 43 is read while the shutter 61 isclosed (low position shown in FIG. 5); then an actuator (not shown)presses the moving equipment 59 against the inlet 37 of a vessel 28.More precisely, the shoe 41 is pressed against the margin 39 of thevessel 28 to be read. The positioning stud 51 ensures accuratepositioning with the opening 67 of the shoe 41 being superposed on theinlet 37 of the vessel 28.

In a first embodiment, the set 26 of vessels 28 rises and lifts themoving equipment. In the preferred embodiment, an actuator lowers thelower plate 47.2, thereby causing the moving equipment 59 to riserelative to the plate 47.

The movement of the moving equipment 59 causes the shutter to open andenables the luminescence present in the vessel 28 to be measured.

The moving equipment 59 moves down relative to the plate 47.2 (as shownin FIG. 5), and the light source 57 is switched on, after which a newmeasurement is performed to verify the light-tightness of the temporarydark chamber formed by the photometric assembly 22 and the vessel 28under measurement. If the luminescence value obtained during thelight-tightness measurement is greater than the value obtained duringthe measurement proper, it is assumed that the result of the measurementis not reliable. The result of the test is rejected, and advantageouslythe test is repeated using the same reaction mixture again with the samesample and the same reagent as deposited in a new vessel 28.

Naturally, testing for light-tightness can be performed prior tomeasuring luminescence without thereby going beyond the ambit of thepresent invention.

Similarly, measuring the voltage level at the output from thephotomultiplier 43 while the shutter 61 is closed can be performedperiodically, but not necessarily for all of the measurements.

The present invention is particularly applicable to detecting thepresence of a chemical or biological substance in a sample.

The present invention applies mainly to medical analysis and research.

1. An automated apparatus for immunological assay, the apparatus comprising: means for supporting, guiding, and displacing a plurality of reaction vessels along a path having a predetermined number of positions, means for supporting samples to be analyzed, means for supporting reagents, means for taking determined quantities of samples and of reagents and for injecting the quantities taken into each of the reaction vessels, means for washing each of the reaction vessels, means for reading results, means for feeding the plurality of reaction vessels and for ejecting the plurality of reaction vessels, means for forming a temporary dark chamber with each reaction vessel, the temporary dark chamber being proof against external light, photometric means for measuring an intensity of light, wherein each reaction vessel includes walls for receiving a sample to be tested, a test reagent, and a substrate coupled with a chemiluminescent substance, each reaction vessel further includes a filling opening, wherein the walls are proof against any light emitted by the chemiluminescent substance, apart from a window for reading the intensity of any light emitted by a reaction mixture formed by the sample to be tested, the reagent, and the substrate, and wherein the window corresponds to the filling opening of each reaction vessel and wherein the window is surrounded by a substantially planar zone against which a light-proof shoe is pressed, and a light source for illuminating, on command, outside of a dark chamber, wherein the photometric means is operable to test the dark chamber for light-tightness, the immunological assay being rejected if the photometric means detects light emitted by the light source.
 2. The apparatus to claim 1, including an opaque shoe for pressing in light-proof manner around the window of the vessel provided with the filling opening for passing light between the vessel and the photometric means.
 3. The apparatus according to claim 1, including a plate for receiving the washing means and the photometric means.
 4. The apparatus according to claim 1, wherein the photometric means includes a moving equipment for pressing the shoe against the window of the vessel.
 5. The apparatus according to claim 1, including a shutter for optically isolating a photoelectric detector and means for measuring electrical values delivered by the photoelectric detector while it is immersed in the dark, wherein the shutter is closed when the photoelectric detector is immersed in the dark.
 6. The apparatus to claim 5, further includes a moving equipment, wherein movement of moving equipment serves to close or open the shutter.
 7. The apparatus to claim 5, wherein the photoelectric detector is a photomultiplier.
 8. A reaction vessel assembly for an automatic chemiluminescence measuring apparatus for immunological assay which includes a photometric device, the assembly comprising: a vessel comprising walls for receiving a sample to be tested, a test reagent, and a substrate coupled with a chemiluminescent substance, and a filling opening, wherein the walls are proof against any light emitted by the chemiluminescent substance, and the filling opening corresponds to a window for reading an intensity of any light emitted by a reaction mixture formed by the sample to be tested, the reagent, and the substrate, and wherein the filling opening is completely surrounded by a planar rim; and a light-proof shoe that is proof against external light and that is directly pressed against the planar rim to form a temporary dark chamber, the shoe being provided with a central opening for passing light between the vessel and the photometric device.
 9. An automated chemiluminescent apparatus for immunological assay, the apparatus comprising: means for supporting, guiding, and displacing a plurality of reaction vessels along a path having a predetermined number of positions, means for supporting samples to be analyzed, means for supporting reagents, means for taking determined quantities of samples and of reagents and for injecting the quantities taken into each of the reaction vessels, means for washing each of the reaction vessels, means for reading a result, means for feeding the plurality of reaction vessels and for ejecting the plurality of reaction vessels, means for forming a temporary dark chamber with each reaction vessel, the temporary dark chamber being proof against external light, the dark chamber having photometric means for measuring an intensity of light, wherein each reaction vessel includes walls for receiving a sample to be tested, a test reagent, and a substrate coupled with a chemiluminescent substance, each reaction vessel further includes a filling opening, wherein the walls are proof against any light emitted by the chemiluminescent substance, and the filling opening corresponds to a window for reading the intensity of any light emitted by a reaction mixture formed by a sample to be tested, the reagent, and the substrate, wherein the filling opening is completely surrounded by a planar rim, a light proof shoe provided with a central opening for passing light between each reaction vessel and the photometric means and being directly pressed against the planar rim, and a light source positioned external to the dark chamber and operable to illuminate, the photometric means operable to detect the light.
 10. The apparatus according to claim 9, including plate for receiving the washing means and the photometric means.
 11. The apparatus according to claim 9, wherein the photometric means includes a moving equipment for pressing the shoe against the window of the vessel.
 12. The apparatus according to claim 9, including a shutter for optically isolating a photoelectric detector and means for measuring electrical values delivered by the photoelectric detector while it is immersed in the dark, wherein the shutter is closed when the photoelectric detector is immersed in the dark.
 13. A method for performing immunological assays that detects light emitted by a reaction mixture consisting of a sample, a reagent and a chemiluminescent substance, said method being performed with an automated chemiluminescent apparatus as set forth in claim 9, said method comprising: combining a sample and a reagent in a chamber of the reaction vessel having a filling opening; adding a chemiluminescent substance to the chamber; pressing a detector directly against the filling opening; measuring the light emitted from the chamber when the detector is pressed against the filling opening to provide a first reading; illuminating a light source external to the chamber; measuring the light emitted from the chamber with the light source illuminating to provide a second reading; and comparing the first reading and the second reading to determine the light-tightness of the chamber. 